1. Field of the Invention
The present invention relates to a method of designing a semiconductor integrated circuit, a designing apparatus, a semiconductor integrated circuit system, a semiconductor integrated circuit mounting substrate, a package and a semiconductor integrated circuit, and more particularly to a method of designing a semiconductor integrated circuit system which designs a semiconductor integrated circuit and reduces an unnecessary radiation (EMI: Electromagnetic Interference), and furthermore, is excellent in a heat characteristic in consideration of a mounting state based on a result of a design of a mounting substrate constituting the semiconductor integrated circuit system.
2. Description of the Related Art
A semiconductor integrated circuit (LSI) has a utilization range enlarged to communicating apparatuses such as a cell phone, general domestic articles, toys and cars in addition to a computer. On the other hand, however, there is a problem in that an unnecessary radiation generated from these products causes a radio interference of a receiving device such as a television or a radio and a malfunction of other systems. A countermeasure for the whole products, for example, filtering or shielding is also taken against the problem. However, it is hard to take the countermeasure in respect of an increase in the number of components, an increase in a cost and the difficulty of a countermeasure to be taken against the product. In the situations, there has been greatly demanded a noise suppression of an LSI system including an LSI package and a mounting substrate mounting the LSI package.
Under the circumstances, the LSI system is positioned as a key device in each product and an increase in a scale and a speed of the LSI system has been required for maintaining a competitive power of the product. While a product cycle is shortened, it is necessary to automate an LSI system design in order to meet these requirements and various studies have been made.
Under present conditions, however, a design flow is usually determined, that is, an LSI is first designed and a package is designed corresponding to the LSI, and a mounting substrate for mounting the package is then designed. In other words, a layout design of the LSI is first carried out and the package is designed corresponding to the layout design of the LSI. Then, the LSI is disposed on the mounting substrate corresponding to an arrangement of an external connecting terminal of the package and a layout design of a wiring pattern to be connected to the external connecting terminal is carried out.
For example, as shown in FIG. 56, a step (S9001) of investigating a system and a specification is executed and an LSI is then designed based on the specification (S9004), and a step of designing a package (S9003) is thereafter executed corresponding to the layout design of the LSI. Subsequently, an arrangement of the LSI on the mounting substrate and a layout design of a wiring pattern to be connected to an external connecting terminal are executed corresponding to the arrangement of the external connecting terminal of the package (a design of the mounting substrate for mounting the package: S9002).
In the LSI design, there is no information about the design of the package and the mounting substrate. Therefore, a consideration cannot be taken and there is a drawback that an intersection of the wiring on the package substrate is caused and a wiring length is increased. For this reason, in some cases, it is necessary to carry out a feedback, that is, the package designing step (S9003) is executed and an input/output pad (I/O) is then disposed again (S9006), and the processing returns to the LSI designing step (S9004), or the mounting substrate designing step (S9002) is executed and the external connecting terminal of the package is then disposed again (S9007), and the processing returns to the package designing step (S9003).
Therefore, there has been proposed a substrate designing apparatus for analyzing a signal when carrying out a substrate layout design in order to decrease a retracing work such as a revision of a design (Patent Document 1).
Patent Document 1: JP-A-11-353339 Publication
However, an LSI design is also carried out corresponding to the internal condition of an LSI and an arrangement of an I/O terminal is also determined by the apparatus described in the Patent Document 1. In the LSI design, there is no layout information about a mounting substrate. For this reason, it is also hard to carry out a design without a feedback.
A scale and an integration of the LSI are continuously increased. There is a problem in that a circuit design of the LSI becomes complicated, and furthermore, the number of external connecting terminals is increased and it is hard to correspond to a change into a multibit with the increase in the scale and integration of the LSI.
Moreover, an arrangement of a signal wiring becomes complicated. For this reason, there is also a problem in that an unnecessary radiation (EMI) analysis and a thermal analysis become complicated, and it is hard to carry out a perfect automation in an optimization of the design, and a manual correction is required, resulting in an increase in a time required for a development.